Part 2: Does prophylactic dextrose gel really work?

Part 2: Does prophylactic dextrose gel really work?

In the first part of this series of posts called Can prophylactic dextrose gel prevent babies from becoming hypoglycemic? the results appeared to be a little lackluster.  The study that this blog post was based on was not perfect and the lack of a randomized design left the study open to criticism and an unbalancing of risks for hypoglycemia.  Given these faults it is no doubt that you likely didn’t run anywhere to suggest we should start using this right away as a protocol in your unit.

Another Study Though May Raise Some Eyebrows

New Zealand researchers who have been at the forefront of publications on the use of dextrose gel recently published another article on the topic Prophylactic Oral Dextrose Gel for Newborn Babies at Risk of Neonatal Hypoglycaemia: A Randomised Controlled Dose-Finding Trial (the Pre-hPOD Study).  As the short study name suggests “Pre-hPOD” this was a preliminary study to determine which dosing of dextrose gel would provide the greatest benefit to prevent neonatal hypoglycemia.  The study is a little complex in design in that there were eight groups (4 dextrose gel vs 4 placebo) with the following breakdown.

Dosing was given either once at 1 h of age (0.5 ml/kg or 1 ml/kg) or three more times (0.5 ml/kg) before feeds in the first 12 h, but not more frequently than every 3 h. Each dose of gel was followed by a breastfeed. The groups given prophylaxis fell into the following risk categories;

IDM (any type of diabetes), late preterm (35 or 36 wk gestation), SGA (BW < 10th centile or < 2.5 kg), LBW (birthweight > 90th centile or > 4.5 kg), maternal use of β-blockers.

Blood glucose was measured at 2 h of age and then AC feeds every 2 to 4 h for at least the first 12 h.  This was continued until an infant had 3 consecutive blood glucose concentrations of 2.6 mmmol/L.  With a primary outcome of hypoglycemia in the first 48 hours their power calculation dictated that a total sample size of 415 babies (66 in each treatment arm, 33 in each placebo arm) was needed which thankfully they achieved which means we can believe the results if they found no difference!

What did they find?

One might think that multiple doses and/or higher doses of glucose gel would be better than one dose but curiously they found that the tried and true single dose of 0.5 mL/kg X 1 offered the best result.  “Babies randomised to any dose of dextrose gel were less likely to develop hypoglycaemia than those randomised to placebo (RR 0.79, 95% CI 0.64–0.98, p = 0.03; number needed to 10.”

Looking at the different cumulative doses, the only dosing with a 95% confidence interval that does not cross 1 was the single dosing.  Higher and longer dosing showed no statistical difference in the likelihood of becoming hypoglycemic in the first 48 hours.  As was found in the sugar babies study, admission to NICU was no different between groups and in this study as with the sugar baby study if one looked at hypoglycemia as a cause for admission there was a slight benefit.  Curiously, while the previous study suggested a benefit to the rate of breastfeeding after discharge this was not noted here.

How might we interpret these results?

The randomized nature of this study compared to the one reviewed in part I leads me to trust these findings a little more than the previous paper.  What this confirms in my mind is that giving glucose gel prophylaxis to at risk infants likely prevents hypoglycemia in some at risk infants and given that there were no significant adverse events (other than messiness of administration), this may be a strategy that some units wish to try out.  When a low blood glucose did occur it was later in the group randomized to glucose gel at a little over 3 hours instead of 2 hours.  The fact that higher or multiple dosing of glucose gel given prophylactically didn’t work leads me to speculate this may be due to a surge of insulin.  Giving multiple doses or higher doses may trigger a normal response of insulin in a baby not at risk of hypoglycemia but in others who might already have a high baseline production of insulin such as in IDMs this surge might lead to hypoglycemia.  This also reinforces the thought that multiple doses of glucose gel in babies with hypoglycemia should be avoided as one may just drive insulin production and the treatment may become counterproductive.

In the end, I think these two papers provide some food for thought.  Does it make sense to provide glucose gel before a problem occurs?  We already try and feed at risk babies before 2 hours so would the glucose gel provide an added kick or just delay the finding of hypoglycemia to a later point. One dose may do the trick though.

A reader of my Facebook page sent me a picture of the hPOD trial which is underway which I hope will definitively put this question to rest.  For more on the trial you can watch Dr. Harding speak about the trial here.

Can prophylactic dextrose gel prevent babies from becoming hypoglycemic?

Can prophylactic dextrose gel prevent babies from becoming hypoglycemic?

I have written a number of times already on the topic of dextrose gels. Previous posts have largely focused on the positive impacts of reduction in NICU admissions, better breastfeeding rates and comparable outcomes for development into childhood when these gels are used. The papers thus far have looked at the effectiveness of gel in patients who have become hypoglycemic and are in need of treatment. The question then remains as to whether it would be possible to provide dextrose gel to infants who are deemed to be at risk of hypoglycemia to see if we could reduce the number of patients who ultimately do become so and require admission.

Answering that question

Recently, Coors et al published Prophylactic Dextrose Gel Does Not Prevent Neonatal Hypoglycemia: A Quasi-Experimental Pilot Study. What they mean by Quasi-Experimental is that due to availability of researchers at off hours to obtain consent they were unable to produce a randomized controlled trial. What they were able to do was compare a group that had the following risk factors (late preterm, birth weight <2500 or >4000 g, and infants of mothers with diabetes) that they obtained consent for giving dextrose gel following a feed to a control group that had the same risk factors but no consent for participation. The protocol was that each infant would be offered a breastfeed or formula feed after birth followed by 40% dextrose gel (instaglucose) and then get a POC glucose measurement 30 minutes later. A protocol was then used based on different glucose results to determine whether the next step would be a repeat attempt with feeding and gel or if an IV was needed to resolve the issue.

To be sure, there was big hope in this study as imagine if you could prevent a patient from becoming hypoglycemic and requiring IV dextrose followed by admission to a unit.  Sadly though what they found was absolutely no impact of such a strategy.  Compared with the control group there was no difference in capillary glucose after provision of dextrose gel (52.1 ± 17.1 vs 50.5 ± 15.3 mg/dL, P = .69).  One might speculate that this is because there are differing driving forces for hypoglycemia and indeed that was the case here where there were more IDMs and earlier GA in the prophylactic group.  On the other hand there were more LGA infants in the control group which might put them at higher risk.  When these factors were analyzed though to determine whether they played a role in the lack of results they were found not to. Moreover, looking at rates of admission to the NICU for hypoglycemia there were also no benefits shown.  Some benefits were seen in breastfeeding duration and a reduction in formula volumes consistent with previous studies examining the effect of glucose gel on both which is a win I suppose.

It may also be that when you take a large group of babies with risks for hypoglycemia but many were never going to become hypoglycemic, those who would have had a normal sugar anyway dilute out any effect.  These infants have a retained ability to produce insulin in response to a rising blood glucose and to limit the upward movement of their glucose levels.  As such what if the following example is at work? Let’s say there are 200 babies who have risk factors for hypoglycemia and half get glucose gel.  Of the 100 about 20% will actually go on to have a low blood sugar after birth.  What if there is a 50% reduction in this group of low blood sugars so that only 10 develop low blood glucose instead of 20.  When you look at the results you would find in the prophylaxis group 10/100 babies have a low blood sugar vs 20/100.  This might not be enough of a sample size to demonstrate a difference as the babies who were destined not to have hypoglycemia dilute out the effect.  A crude example for sure but when the incidence of the problem is low, such effects may be lost.

A Tale of Two Papers

This post is actually part of a series with this being part 1.  Part 2 will look at a study that came up with a different conclusion.  How can two papers asking the same question come up with different answers?  That is the story of medicine but in the next part we will look at a paper that suggests this strategy does work and look at possible reasons why.

Capnography or colorimetric detection of CO2 in the delivery suite.  What to choose?

Capnography or colorimetric detection of CO2 in the delivery suite. What to choose?

For almost a decade now confirmation of intubation is to be done using detection of exhaled CO2. The 7th Edition of NRP has the following to say about confirmation of ETT placement “The primary methods of confirming endotracheal tube placement within the trachea are detecting exhaled CO2 and a rapidly rising heart rate.” They further acknowledge that there are two options for determining the presence of CO2 “There are 2 types of CO2 detectors available. Colorimetric devices change color in the presence of CO2. These are the most commonly used devices in the delivery room. Capnographs are electronic monitors that display the CO2 concentration with each breath.” The NRP program stops short of recommending one versus the other. I don’t have access to the costs of the colorimetric detectors but I would imagine they are MUCH cheaper than the equipment and sensors required to perform capnography using the NM3 monitor as an example. The real question though is if capnography is truly better and might change practice and create a safer resuscitation, is it the way to go?

Fast but not fast enough?

So we have a direct comparison to look at. Hunt KA st al published Detection of exhaled carbon dioxide following intubation during resuscitation at delivery this month. They started from the standpoint of knowing from the manufacturer of the Pedicap that it takes a partial pressure of CO2 of 4 mm Hg to begin seeing a colour change from purple to yellow but only when the CO2 reaches 15 mm Hg do you see a consistent colour change with that device. The capnograph from the NM3 monitor on the other hand is quantitative so is able to accurately display when those two thresholds are reached. This allowed the group to compare how long it took to see the first colour change compared to any detection of CO2 and then at the 4 and 15 mm Hg levels to see which is the quicker method of detection. It is an interesting question as what would happen if you were in a resuscitation and the person intubates and swears that they are in but there is no colour change for 5, 10 or 15 seconds or longer? At what point do you pull the ETT? Compare that with a quantitative method in which there is CO2 present but it is lower than 4. Would you leave the tube in and use more pressure (either PIP/PEEP or both?)? Before looking at the results, it will not shock you that ANY CO2 should be detected faster than two thresholds but does it make a difference to your resuscitation?

The Head to Head Comparison

The study was done retrospectively for 64 infants with a confirmed intubation using the NM3 monitor and capnography.  Notably the centre did not use a colorimetric detector as a comparison group but rather relied on the manufacturers data indicating the 4 and 15 mm Hg thresholds for colour changes.  The mean age of patients intubated was 27 weeks with a range of 23 – 34 weeks.  The results I believe show something quite interesting and informative.

Median time secs (range)
Earliest CO2 detection 3.7 (0 – 44s)
4 mm Hg 5.3 (0 – 727)
15 mm Hg 8.1 (0 – 727)

I wouldn’t worry too much about a difference of 1.6 seconds to start getting a colour change but it is the range that has me a little worried.  The vast majority of the patients demonstrated a level of 4 or 15 mm Hg within 50 seconds although many were found to take 25-50 seconds.  When compared to a highest level of 44 seconds in the first detection of CO2 group it leads one to scratch their head.  How many times have you been in a resuscitation and with no CO2 change you keep the ETT in past 25 seconds?  Looking closer at the patients, there were 12 patients that took more than 30 seconds to reach a threshold of 4 mm Hg.  All but one of the patients had a heart rate in between 60-85.  Additionally there was an inverse relationship found between gestational age and time to detection.  In other words, the smallest of the babies in the study took the longest to establish the threshold of 4 and 15 mm Hg.

Putting it into context?

What this study tells me is that the most fragile of infants may take the longest time to register a colour change using the colorimetric devices.  It may well be that these infants take longer to open up their pulmonary vasculature and deliver CO2 to the alveoli.  As well these same infants may take longer to open the lung and exhale the CO2.  I suppose I worry that when a resuscitation is not going well and an infant at 25 weeks is bradycardic and being given PPV through an ETT without colour change, are they really not intubated?  In our own centre we use capnometry in these infants (looks for a wave form of CO2) which may be the best option if you are looking to avoid purchasing equipment for quantitative CO2 measurements.  I do worry though that in places where the colorimetric devices are used for all there will be patients who are extubated due to the thought that they in fact have an esophageal intubation when the truth is they just need time to get the CO2 high enough to register a change in colour.

Anyways, this is food for thought and a chance to look at your own practice and see if it is in need of a tweak…

Is skin to skin care truly good for the developing brain?

Is skin to skin care truly good for the developing brain?

Skin to skin care or kangaroo care is all the rage and I am the first one to offer my support for it.  Questions persist though as to whether from a physiological standpoint, babies are more stable in an isolette in a quiet environment or out in the open on their mother or father’s chests. Bornhorst et al expressed caution in their study Skin-to-skin (kangaroo) care, respiratory control, and thermoregulation.  In a surprising finding, babies with an average gestational age of 29 weeks were monitored for a number of physiological parameters and found to have more frequent apnea and higher heart rates than when in an isolette.  The study was small though and while there were statistical differences in these parameters they may not have had much clinical significance (1.5 to 2.8 per hour for apnea, bradycardia or desaturation events).  Furthermore, does an increase in such events translate into any changes in cerebral oxygenation that might in turn have implications for later development?  Tough to say based on a study of this magnitude but it certainly does raise some eyebrows.

What if we could look at cerebral oxygenation?

As you might have guessed, that is exactly what has been done by Lorenz L et al in their recent paper Cerebral oxygenation during skin-to-skin care in preterm infants not receiving respiratory support.The goal of this study was to look at 40 preterm infants without any respiratory distress and determine whether cerebral oxygenation (rStO2)was better in their isolette or in skin to skin care (SSC).  They allowed each infant to serve as their own control by have three 90 minute periods each including the first thirty minutes as a washout period.  Each infant started their monitoring in the isolette then went to SSC then back to the isolette.  The primary outcome the power calculation was based on was the difference in rStO2 between SSC and in the isolette.  Secondary measures looked at such outcomes as HR, O2 sat, active and quiet sleep percentages, bradycardic events as lastly periods of cerebral hypoxia or hyperoxia.  Normal cerebral oxygenation was defined as being between 55 to 85%.

Surprising results?

Perhaps its the start of a trend but again the results were a bit surprising showing a better rStO2 when in the isolette (−1.3 (−2.2 to −0.4)%, p<0.01).  Other results are summarized in the table below:

Mean difference in outcomes
Variable SSC Isolette Difference in mean p
rStO2 73.6 74.8 -1.3 <0.01
SpO2 (median) 97 97 -1.1 0.02
HR 161 156 5 <0.01
% time in quiet sleep 58.6 34.6 24 <0.01

No differences were seen in bradycardic events, apnea, cerebral hypoexmia or hyperoxemia.  The authors found that SSC periods in fact failed the “non-inferiority” testing indicating that from a rStO2 standpoint, babies were more stable when not doing SSC!  Taking a closer look though one could argue that even if this is true does it really matter?  What is the impact on a growing preterm infant if their cerebral oxygenation is 1.3 percentage points on average lower during SSC or if their HR is 5 beats per minute faster?  I can’t help but think that this is an example of statistical significance without clinical significance.  Nonetheless, if there isn’t a superiority of these parameters it does leave one asking “should we keep at it?”

Benefits of skin to skin care

Important outcomes such as reductions in mortality and improved breastfeeding rates cannot be ignored or the positive effects on family bonding that ensue. Some will argue though that the impacts on mortality certainly may be relevant in developing countries where resources are scarce but would we see the same benefits in developed nations.  The authors did find a difference though in this study that I think benefits developing preterm infants across the board no matter which country you are in.  That benefit is that of Quiet Sleep (QS).  As preterm infants develop they tend to spend more time in QS compared to active sleep  (AS).  From Doussard- Roossevelt J, “Quiet sleep consists of periods of quiescence with regular respiration and heart rate, and synchronous EEG patterns. Active sleep consists of periods of movement with irregular respiration and heart rate, and desynchronous EEG patterns.”  In the above table one sees that the percentage of time in QS was significantly increased compared to AS when in SSC.  This is important as neurodevelopment is thought to advance during periods of QS as preterm infants age.

There may be little difference favouring less oxygen extraction during isolette times but maybe that isn’t such a good thing?  Could it be that the small statistical difference in oxygen extraction is because the brain is more active in laying down tracks and making connections?  Totally speculative on my part but all that extra quiet sleep has got to be good for something.

To answer the question of this post in the title I think the answer is a resounding yes for the more stable infant.  What we don’t know at the moment except from anecdotal reports of babies doing better in SSC when really sick is whether on average critically ill babies will be better off in SSC.  I suspect the answer is that some will and some won’t.  While we like to keep things simple and have a one size fits all answer for most of our questions in the NICU, this one may not be so simple.  For now I think we keep promoting SSC for even our sick patients but need to be honest with ourselves and when a patient just isn’t ready for the handling admit it and try again when more stable.  For the more stable patient though I think giving more time for neurons to find other neurons and make new connections is a good thing to pursue!

Oh the places you'll go

Oh the places you'll go

It is hard to be a Neonatologist who took the path through Pediatrics first and not use a Dr. Seuss quote from time to time.  e26a79ea-90a6-4d2c-b748-107583da3b3a_1-c8a62a7c18ba4bbc0bcfb40c1c3e4d16.jpegIf your unit is anything like ours where you work I imagine you feel as if you are bursting at the seams.  As the population grows so do our patient volumes.  I often quote the number 10% as being the number of patients we see out of all deliveries each year in our units.  When I am asked why our numbers are so high I counter that the answer is simple.  For every extra 100 births we get 10 admissions. It is easy though to get lost in the chaos of managing a unit in such busy times and not take a moment to look back and see how far we have come.  What did life look like 30 years ago or 25 years ago?  In Winnipeg, we are preparing to make a big move into a beautiful new facility in 2018. This will see us unify three units into one which is no easy task but will mean a capacity of 60 beds compared to the 55 operational beds we have at the moment.

In 2017 we are routinely resuscitating infants as young as 23 weeks and now with weights under 500g at times.  Whereas in the past anyone under 1000g was considered quite high risk, now the anticipated survival for a 28 week infant at 1000g is at or above 95%.  Even in my short career which began in 1998 in terms of Pediatrics and then 2001 in Neonatology our approach in terms of comfort with the smallest infants has eased greatly.  What inspired this post though was a series of newspaper clippings from 1986 and 1991 that made me take a moment to look up at the sky and mutter “huh”.  When you take a trip down memory lane and read these posts I think you will agree we have come a LONG way and (in truth) in a very short time.

1986 – Opening of the New NICU at Children’s Hospital

Newspaper clipping

This unit was built with 3.5 million dollars.  Imagine how far that would go now…

The unit had a capacity of 18 beds but opened with only 12 and a nursing staff of 60 (compare that to 150 now!).  They couldn’t open more beds due to the lack of available nurses with sufficient skills.

My favourite comment to provide some perspective was that 5 to 10 years before this time the estimated survival for infants under 1000g was 15%!

Have we ever come a long way in family centred care.  Can you imagine having a baby born now at 695g whose family wouldn’t get to hold them till almost 3.5 months of age?!  That is what happened in the case described in this article.

1991 – Opening of the new Intermediate Care Nursery

Chronicle page 1Chronicle page 2

Did you know the old unit had 19 beds (was originally 9 babies) and expanded to 27 at this time?

It cost 3.1 million to build this unit.

The long and the short of it is that yes things are busy and in fact busier than they have ever been.  Do not lose sight however wherever your practice is that you are part of a story for the ages.  Things that were once thought impossible or miracles are now everyday events and you have been part of it.  For those of you who read this post this will likely bring about a lot of nostalgia for you.  Thirty years in medicine is not a long time and we have accomplished so much along the way.  For those of you who are just starting out, imagine where we will be in 30 years from now.  I for one can’t wait to read about it and wonder where we will have gone by then.